Stripping punch



JQ S. BOZEK Aug. 18, 1970 STRIPPING PUNCH Filed Feb. 5, 1968 United States Patent O M' 3,524,338 STRIPPING PUNCH John S. Bozek, Chicago, Ill., assignor to Continental Can Company, Inc., New York, N.Y., a corporation of New York Filed Feb. 5, 1968, Ser. No. 702,939 Int. Cl. B21d 45/00 U.S. Cl. 72-345 8 Claims ABSTRACT F THE DISCLOSURE This disclosure relates to a punch for automatically stripping articles therefrom, and includes a main tubular body having a fluid cylinder at one end and a nose at an opposite end, the nose being connected by a piston rod to a piston within the cylinder, and a closed fluid pressure system acting against the piston to extend the nose to automatically strip a drawn article from the punch.

A primary object of this invention is to provide a novel punch for manufacturing drawn or wall ironed articles, the punch including a main body secured at one end to a fluid cylinder and carrying at an opposite end thereof an extendible and retractable nose, the nose being connected to a piston within the cylinder by a piston rod, and a closed uid pressure system for normally urging the nose to its extended position whereby after the nose is moved to its retracted position by forces developed during a drawing operation the pressure of the uid pressure system automatically extends the nose to cause a drawn article to be stripped therefrom.

A further object of this invention is to provide a novel punch of the type described wherein means are additionally provided for directing uid pressure against the interior of a drawn article carried by the punch to augment the stripping thereof upon the movement of the nose to its extended position.

Still another object of thisI invention is to provide a novel punch of the type heretofore described wherein the fluid pressure directing means can alternatively function as means for venting air to the atmosphere from within an article during the drawing thereof.

With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claimed subject matter, and the several views illustrated in the accompanying drawing.

In the drawing:

FIG. 1 is a fragmentary side elevational view with parts broken away and shown in section of a novel punch of this invention, and illustrates a nose carried by a reciprocally mounted piston rod with the nose being illustrated in its retracted position.

FIG. 2 is an enlarged fragmentary sectional view of the lower end of the punch of FIG. 1, and illustrates the nose in its extended positon in which a drawn body is automatically stripped from the punch.

A novel punch constructed in accordance with this invention is fully illustrated in FIG. l of the drawing, and is generally designated by the reference numeral 10. The punch includes a two-piece main tubular body 11 formed by a pair of tubular sleeves 12, 13 threadably secured together at 14. The tubular body 11 includes a bore 1-5 which is counterbored at opposite ends to -form seats for a pair of bushings 16, 17. Adjacent the counterbore (unnumbered) in which the bushing 17 is housed is an additional counterbore 18.

A nose 20 (FIG. 2) is mounted for sliding movement in the counterbore 18 between a retracted position (FIG. 1) and an extended position (FIG. 2). The nose 20 in- 3,524,338 Patented Aug. 18, 1970 cludes a base portion 21, a peripheral skirt 22 and a radially outwardly directed peripheral flange 23 which is provided with a rounded end face 24 and a at annular surface 25 which axially opposes a flat annular surface 26 of the main body 11. A reduced end portion 28 of a piston rod 30 is threadably received in a threaded bore 31 of the nose base 21 and is secured thereto by a locking nut 32. The base portion 21 and the flange 23 of the nose 20 each includes a plurality of equally circumferentially spaced bores 33, 34, respectively.

The upper end portion of the main body 11 includes a reduced threaded end portion 35 which is threadably secured in a threaded bore 36 of a uid cylinder 37. The iluid cylinder 37 is in turn secured by a plurality of bolts 38, only one of which is illustrated, to a ram 40 of a conventional press (not shown). A piston 41 having opposite faces 42, 43 is housed within a fluid chamber 44 of the cylinder 37, and a threaded bore of the piston is secured to a threaded reduced end portion 45 of the piston rod 30. A plug 46 prevents fluid communication between an axial bore 47 of the piston rod 30 and the portion of the chamber 44 above the piston face 42. The bore 47 is, however, placed in iluid communication between the portion of the chamber beneath the face 43 and an annular chamber between the piston rod 30 and the main tubular body 11 by a pair of radial ports 50, 51. The same annular chamber is also placed in lluid communcation with an axial bore 52 (FIG. 2) at the lower end portion of the piston rod 30 by means of a radial port 53.

The side of the chamber 44 above the face 42 of the piston 41 is placed in fluid communication with a closed fluid pressure system 55 by means of a passage 56 in the cylinder 37, a conduit 57, a conventional accumulator 58, and a one-way check valve 60= which is connected to a conventional source of air pressure as, for example, a conventional compressor.

The portion of the chamber `44 beneath the end face 43 of the piston 41 is likewise connected to a source of air pressure or atmosphere by means of a passage l61, a conduit 62 and a two-position valve 63 which can be manually or automatically manipulated to place the conduit 62 in communication with compressed air or the atmosphere.

A typical operation of the punch 10 is begun by opening the check valve y60 of the closed fluid pressure system causing compressed air to enter the portion of the chamber 44 above the piston 41 whereupon after the build-up of a predetermined pressure within the system 55, the valve 60 is closed. At this point the piston 41 is, of course, in its lowermost position and the nose 20' is extended to the position illustrated in FIG. 2.

Assuming that a cup-shaped metallic blank is to be drawn or wall ironed, the blank is positioned in axial alignment with the punch and with the die opening (or openings) or one or a plurality of female drawing or wall ironing dies (not shown). As the ram 40 descends the extended nose 20 and the lower end portion of the main body 11 enter the cup-shaped blank and begin forcing the blank through the female die. As the blank begins moving through the female die the friction forces developed by the drawing or wall ironing operation and acting through the blank cause the blank and the nose 20 to be forced upwardly, the latter into the counterbore 18, as shown in FIG. l, at which point the surfaces 25, 26 are in abutment. The movement of the nose 20- to its retracted position forces the piston 41 to the position illustrated in FIG. 1 with the increase in fluid pressure in the system 55 being accommodated by the accumulator 58.

Due to the contact between the surfaces 25, 26, the nose 20 and the main body 11 are essentially equivalent to a rigid punch and during the continued simultaneous downward movement of the nose 20 and the body 11,

the cup-shaped blank is progressively forced through the opening of the female die forming a drawn or wall ironed article C, which may be a can body or similar container. After the uppermost edge of the article C has passed beyond the female die opening the frictional and other forces of the drawing or wall ironing operation are terminated. At this time the forces tending to retain the article C upon the punch are overcome by the pressure within the fluid system 55 which, acting against the face 42 of the piston 41, forces the latter downwardly along with the piston rod 30 and the nose 20 to the position shown in FIG. 2 whereupon the nose 20 strips the article C from the end of the main body 11 by moving the article C axially downwardly, as shown in FIG. 2. Upon reaching the position shown in FIG. 2, gravity alone will in most cases be sufcient to cause the article C to simply drop oif the end of the punch 10.

It should be noted that during the retraction of the nose 20 into the counterbore 18 any air which might otherwise become entrapped or compressed in the counterbore 18 or between the faces 25, 26 is vented to atmosphere through the bores 33, 34, the axial bore 52, the radial port 53, the annular gap between the piston rod 30 and the main tubular body 10, the radial port 51, the bore 47, the radial port 50, the portion of the chamber 44 beneath the piston face `43, the passage 61, the conduit 62 and the valve 63 positioned in the manner illustrated in FIG. 1. During the downward movement of the piston 41 incident to the stripping operation, air which otherwise might become entrapped beneath the face 43 of the piston 41 is also Vented to atmosphere through the passage 61, the conduit 62 and the valve 63 in the position as shown in FIG. 1.

In order to augment the stripping operation of the nose 20, it might be found desirable to assist the stripping operation by blowing the article C from oif the end of the punch when positioned as shown in FIG. 2. To this end the valve 63 may be automatically or manually rotated to place the conduit 62 in fluid communication with a source of compressed air which will be conducted into the interior of the article C over a path defined by the source of compressed air, the valve 63, the conduit 62, the passage 61, the portion of the chamber 44 beneath the piston 41, the port 50, the bore 47, the port 51, the annular area between the piston rod 30 and the main tubular body 11, the port 53 and the bore 52. During this blowing operation it will be noted that the piston 41 is in its lowermost or bottom position at which point outermost anges (unnurnbered) of the piston 41 contact the opposing face (unnumbered) of the chamber 44. However, due to the relieved or recessed construction of the face 43 the air pressure delivered into the chamber 44 is readily conducted into the port 50.

While the operation of the punch 10 has been described in conjunction with the closed uid system 55 and its accumulator 58, it is to be understood that the accumulator need not be a part of the uid system 55 and in lieu thereof the conduit 57 could be directly connected to the check valve 60, which in this case is preferably a solenoid actuated valve. By positioning microswitches on the press or a pressure responsive valve in the line 57, the air pressure can be continually monitored and the solenoid valve 60 opened periodically to maintain the air pressure in the closed system at the desired level.

While preferred lforms and arrangements of parts have been shown in illustrating the invention, it is to be clearly understood that various changes in details and arrangement of parts may be made without departing from the spirit and scope of the invention as defined in the appended claimed subject matter.

I claim:

1. A punch for manufacturing drawn articles comprising a main body adapted to be connected to a reciprocal press ram, a nose mounted at an end of said body for axial movement between extended and retracted positions, means for normally urging said nose to its extended position, and said urging means is a closed fluid system continuously pressurized during reciprocation of said body by said ram whereby the nose is moved to its retracted position by forces greater than that applied to said nose by said fluid pressure system developed during the drawing operation which overcome the pressure of the fluid pressure system and upon the termination of the drawing forces the pressure of the uid pressure system automatically moves the nose to its extended position causing the drawn article to be stripped from the punch.

2. The punch as defined in clairn 1 including means for directing fluid pressure against the interior of a drawn article carried by the punch to augment the stripping thereof upon the movement of said nose to its extended position.

3. The punch as defined in claim 1 wherein said main body includes a fluid cylinder at an end thereof opposite said nose, a piston n said cylinder, said fluid pressure system being connected to said cylinder to normally bias said piston in a direction toward said nose, and a means connecting said piston to said nose.

4. The punch as defined in claim 1 wherein said main body is tubular, a rod is mounted for reciprocal movement in said main body, and said nose is carried by said rod.

5. A punch for manufacturing drawn articles comprising a main tubular body having opposite ends, a uid cylinder at one of said ends and a nose at the other of said ends adapted to be moved between extended and retracted positions relative to said main body, a piston in said cylinder, a piston rod connected to said piston and said nose, means for introducing iluid pressure into said uid cylinder behind a face of said piston which is remote from said nose, means for introducing fluid pressure into said uid cylinder behind the opposite face of said piston, and means for directing the uid pressure so introduced behind said opposite face against the interior of a drawn article carried by the punch to augment the stripping thereof upon the movement of said nose to its extended position.

6. The punch as defined in claim 5 wherein said nose is at al1 times at least partially telescopically received in said other end of said main body.

7. The punch as defined in claim 5 including means for venting air to the atmosphere from within an article during the drawing thereof. l'

8. The punch as deiined in claim 5 wherein said fluid pressure directing means can alternately function as means for venting air to the atmosphere from within an article during the drawing thereof.

References Cited UNITED STATES PATENTS 601,738 4/ 1898 Stampacchia. 1,747,463 2/1930 Booth 72-345 2,731,140 1/1956 May 72-347 3,270,544 9/ 1966 Maeder et al. 3,312,098 4/ 1967 Henrickson et al 72-349 RICHARD J. HERBST, Primary Examiner 

